Wind Chill (approx)

This formula estimates the "felt" air temperature on exposed skin when cold air and wind act together. Wind strips away the thin layer of warmer air next to the body and increases convective heat loss, so the perceived temperature drops faster than the thermometer reading alone would suggest. The equation is an empirical fit to observations in cold conditions, so it is useful for estimating human comfort and frostbite risk rather than for exact thermodynamic calculations.

Use this when you want a quick estimate of how cold outdoor conditions will feel to a person in chilly, windy weather, especially in winter safety planning. It is most appropriate for sub-freezing or near-freezing temperatures and moderate-to-strong wind speeds.

• Using wind chill for hot weather or calm conditions, where it is not meaningful
• Forgetting that wind speed must be in km/h, not m/s or mph
• Treating the result as an actual air temperature rather than a perceived temperature for exposed skin